This invention relates to brake apparatuses for bicycle, of the known type, comprising:
a front wheel braking device of the bicycle comprising:
a front brake, and
a front brake control device, comprising:
a supporting body,
a front brake control lever articulated around the supporting body and,
a transmission connecting the front brake and the front brake control lever, and
a rear wheel braking device of the bicycle comprising:
a rear brake, and
a rear brake control device, comprising:
a supporting body,
a rear brake control lever articulated around the supporting body and,
a transmission connecting the rear brake and the rear brake control lever.
In bicycles, as in all vehicles, the force by which the front wheel is pressed on the ground increases and the force by which the rear wheel is pressed on the ground decreases during braking, reason for which the grip of the rear wheel with respect to the ground is reduced with respect to the front wheel in equal conditions of friction. In other words, the maximum braking action which can be applied to the front wheel without locking it and causing it to slip on the ground is higher than that applicable to the rear wheel. Consequently, when braking to the limit of grip, the necessity of differentiating between the braking action of the front wheel and the rear wheel arises. On conventional bicycles, the front brake and the rear brake are controlled by means of two separate levers which are operated manually, reason for which, in theory, cyclists can employ their sensitivity and apply a different braking force on the front wheel and on the rear wheel. However, firstly, not all cyclists have the sensitivity to control the front wheel and the rear wheel in a differentiated fashion to obtain the maximum possible braking without locking the wheels. Secondly, in emergency conditions, i.e. when the maximum possible braking must be applied in the shortest possible time, this result is not achievable.
In order to account for these requirements, various braking systems for bicycles have been proposed in the past which comprise a centralised control device to operate the front brake and the rear brake at the same time. This device is connected to the two brakes by means of the respective conformed transmissions and arranged in such a way to obtain two different braking actions on the front wheel and on the rear wheel from a single control action. However, these devices are not very commonly implemented both because they are relatively complicated and because cyclists always prefer having two available separate brake controls for the front wheel and for the rear wheel, especially in the case of competition bicycles.
In order to solve all of the aforesaid problems, this invention relates to a brake apparatus for bicycle comprising:
a front wheel braking device of the bicycle comprising:
a front brake, and
a front brake control device, comprising:
a supporting body,
a front brake control lever articulated around the supporting body and,
a transmission connecting the front brake and the front brake control lever, and
a rear wheel braking device of the bicycle which is fully independent from the front wheel braking device comprising:
a rear brake, and
a rear brake control device, comprising:
a supporting body,
a rear brake control lever articulated around the supporting body and,
a transmission connecting the rear brake and the rear brake control lever characterised in that the front braking device is capable of applying a braking force on the front wheel which is higher than that applied on the rear wheel given the same force exerted on the levers controlling the front brake and the rear brake.
In order to achieve this, this invention moves against a technical prejudice which has existed to the current day. This is because, the proposed forms of embodiment aimed at obtaining differentiated braking of the two wheels of a bicycle always comprised a centralised control suitable for causing in any way a different braking action on the two wheels of the bicycle. Conversely, in the case of this invention, two fully separate braking devices for the front wheel and the rear wheel are still used, but these braking devices are conformed to exert two different braking actions (specifically, a higher braking action on the front wheel) given the same control force exerted on the control lever of the front brake and on the control lever of the rear brake.
In a first form of embodiment, this result is obtained by mutually differentiating the brake and the rear brake. Particularly, in the apparatus according to this invention, the front brake is a so-called xe2x80x9cdual-pivotxe2x80x9d brake. The term xe2x80x9cdual-pivotxe2x80x9d here is used to intend, for example, a brake of the type described and illustrated in U.S. Pat. No. 5,425,434 by the Applicant. This brake comprises two arms holding respective brake shoes, where a first arm is articulated around a first pivot pin, secured to the bicycle frame, and the second arm is articulated around a second pivot pin, spaced from the first pivot pin and held by an auxiliary support, which in turn is rigidly secured to the bicycle frame. Furthermore, a rocking member is arranged between the two arms to multiply the braking load. According to this first form of embodiment of the invention, the rear brake, on the contrary, is a conventional brake with a single pivot pin, where the two arms holding the brake shoes are mutually articulated around the same pin secured to the frame of the bicycle. Naturally, given equal dimensioning of the dual-pivot brake and of the single pivot brake, the braking action obtained on the wheel for the same force applied to the control wire of the brake is higher in the case of the dual pivot brake. In this way, cyclists can avail of a brake apparatus which always ensures higher braking of the front wheel easily permitting to obtain the maximum possible braking efficiency in all conditions of grip with ground, in all cases always offering cyclists the possibility to separately control the front brake and the rear brake.
In a second form of embodiment of this invention, the front braking device and the rear braking device is differentiated by means of a different positioning of the point of the brake control lever to which the respective control wire is connected. This solution naturally refers to the conventional case in which the transmission connecting each control lever to the respective brake consists of a flexible wire, with one extremity connected to the control lever in a point of the lever which is situated on the opposite side of the pivoting axis of the lever with respect to the actuation end of the lever. In the case of this invention, the control lever of the front brake is connected to the respective flexible wire in a point which is closer to the pivoting axis of the lever with respect to the case of the rear brake control lever. Thanks to this characteristic, given the same force exerted on the actuation end of the control lever, the control lever of the front wheel generates on the flexible wire a higher force with respect to the case of the control lever of the rear brake.